Oscillator construction



DeC- 25, 1951 E. M. osTLuND 2,579,511

oscxLLAToR CONSTRUCTION I Filed May 24, 1945 INVENTOR.

EVE/W M. 'asn wm Patented Dec. 25,1951

OSCILLATOR CONSTRUCTION Evert M. Ostlund, Montclair, N. J., assigner toFederal Telephone and Radio Corporation, New York, N. Y., a corporationof Delaware Application May 24, 1945, Serial No. 595,515

16 Claims.

The present invention relates to the construction of oscillatorsparticularly of the coaxial line type.

To obtain maximum efciency from an oscillator, the feed-back must becontrolled. In internal feed-back arrangements, where energy is fed backthrough the inter-electrode capacities vof the vacuum tubes used,control of the feedback becomes difiicult because the inter-electrodecapacities are fixed. External feed-back arrangements have the advantagethat they may be tuned, and in general tuned feed-back arrangementsprovide greater excitation than untuned ones. In order, however, toprovide optimum operation over a band of frequencies, the tuning of thefeed-back arrangement should be capable of being varied over the band offrequencies covered.

An object of the present invention is the provision of an `improvedcoaxial line oscilla-tor of the external feed-back type.

Another object of the present Ainvention is the provision in anoscillator of improved external inductive feed-back means adapted to betuned over a'band of `frequencies.

Another object of the present invention is the provision in anoscillator, of external inductive feed-back means which iscorrespondingly tuned over a band of frequencies by the tuning of theinput and .output circuits of the oscillator over said band.

Other and further objects of the present invention .will become apparentand the invention will be best understood from the followingdescription-.of embodiments thereof. reference being had to thedrawings, in which:

Fig. Yl. is `a partially -schematic and partially sectional view of acoaxial line oscillator embodying my invention;

Fig. 2:is a section taken along the line 2-2 of Fig. .1;

Fig. .3 is a fragmentary elevational view, partly broken away, of -amodification of the structure illustrated in Fig. 1; and

Fig. 41s ,a fragmentary sectional view of another modlfication of .thestructure illustrated in Fig. 1.

Referringnow to Figs. 1 and 2, the coaxial line structure thereillustrated includes an electron discharge device or vacuum tube Ihaving an ano de 2, a .grid 3, and a cathode 4. The` anode is coupledtoa hollow elongated cylindrical conductor -5 and the cathode 4 iscoupled through condenser 6 to asimilar cylindrical conductor Conductors5 and 1 are ythe yinner conductors of coaxial lines 8 and 9 respectivelywhose outer conductors, cylindrical members iii and II are coupledtogether and completely surround and shield the inner conductors and thetube I.

Tube I is preferably of the type in which the grid and its lead serve asan electrostatic shield between the anode and its lead and the cathodeand its leads, as for example, in the lighthouse tube. Grid 3 isconnected to a grid disc I2 which extends between flanged portions I3and It respectively of the external conductors it and II and isseparatedfrom said flanged portions by insulation, generally designatedby the numeral I5. This arrangement forms a capacity between the gridand the outer conductors I and II. Depending upon the Value of thiscapacity, a certain amount of feed-back may be introduced between theanode coaxial line 8 and the cathode coaxial line 9. Said coaxial lines3 and 9 are preferably short-circuited at their outer ends by conductivediscs I6 rand. Il respectively.

In accordance with one embodiment of my invention, external feed-backmeans are provided as follows: four rods It, It, 2t and 2l aresymmetrically arranged, as shown in Fig. 1, equidistant from each otherbetween the inner conductors 5 and i and the outer conductors It and IIand extending substantially from disc It to disc I through suitableopenings 22 vin the grid disc I2. Rods 8-2 I, being conductors, serve asfeed-back means feeding back energy from the anode coaxial line tV tothe cathode coaxial line 9.

Since the oscillator arrangement here described is designed to operateover a band of frequencies, I have provided, in accordance with myinvention, means forY tuning the coaxial lines 8 and Sand the feed-backconductors lil-2 I For this purpose I prefer to'provide slidable discs23 and 24 in coaxial lines t and 9. Each of said discs is conductive andis provided with openings through which the rods i8-2I pass, saidopenings being provided with spring fingers, generally designated by thenumeral 25, which make contact with the rods as discs 23 and 24 are slidtherealong. Spring fingers 25 are provided adjacent the perimeter oieach of the discs 23 and 24 and make contact ,with the inner surface oftheouter conductors IB and I I respectively, while similar fingers 21are provided at the central opening 28 of discs 23 and 2li to makecontact with the inner conductors 5 and 'l respectively.

By varying the position ofthe discs 23 and 24, the effective length ofthe various conductors, that is the inner conductors 5 and l, the outerconductors v8 and 9 andthe rods I8-2I may be varied. By selecting theproper number of rods and their diameters in relation to the otherconstants of the oscillator, optimum feed-back is obtained over a rangeof frequencies. The position of discs 23 and 24 may be changed by meansof rods 29 and 3U extending through suitable openings in end discs I6and I'I respectively. These rods are of insulating material.

While in the embodiment illustrated in Figs. `1 and 2, the feed-back iscontrolled by slidable discs 23 and 24 respectively which simultaneouslyvary the tuning of the associated coaxial lines 8 and 9, in certaininstances it is desirable to have additional independent means forcontrolling the feed-back. In the modification illustrated in Fig. 3,each of the rods I8--2I is independently tuned by one of four coaxialline tuning stubs 3|, each having an inner conductor 32 connected withits y associated feed-back rod and whose outer conductor 33 is connectedwith the outer conductor Il of the coaxial line. Tuning stubs 3| areeach provided with tuning means such as a slidable shorting tuner 34.Adjustment of the position of tuner 34 varies the energy fed backindependently of the tuning by discs 23 and 24.

In the other modification illustrated in Fig.

4, independent tuning of the feed-back rods isA accomplished byinterposing a tuning stub 35 effectively between each of the feed-backrods and the disc 23 so that the rod serves as the inner conductor ofthe stub and passes through an opening 3B provided in the disc 23 whilethe outer conductor 31 of the tuning stub is connected with the disc 23about said opening 35. Adjustment of the tuning element 38 of the stubvaries the energy fed back independently of the tuning of the coaxiallines. Similar stubs may be associated in like manner with disc 24.

While I have described hereinabove the details of one constructionembodying my invention, it will be obvious to those versed in the artthat numerous changes may be made in the details thereof withoutdeparting from the teachings of my invention. Therefore, while I havedescribed above the principles of my invention in connection with specicapparatus, it is to be clearly understood that this description is madeonly by Way of example and not asa limitation on the scope of myinvention as dened in the accompanying claims.

I claim:

l. A transmission line oscillator comprising an electron dischargedevice including an anode, cathode, and grid, a cathode transmissionline coupled to the cathode, an anode transmission line coupled to theanode, feed-back means comprising a linear conductor operativelyassociated with both said transmission lines, and movable conductormeans connected across said transmission lines and to said linearconductor for tuning the transmission lines and for varying theeffective length of the linear conductor to thereby control thefeed-back.

2. A coaxial line oscillator comprising an electron discharge deviceincluding an anode, cathode, and grid, a cathode inner conductor coupledto the cathode, an anode inner conductor coupled to the anode, outerconductors surrounding said inner conductors and coaxial therewith, saidouter conductors being coupled to the grid, feedback means comprising asingle linear conductor member having a portion thereof extendingbetween the cathode inner conductor and its outer conductor and theremainder extending between 4, the anode inner conductor and its outerconductor.

3. A coaxial line oscillator according to claim 2 wherein said linearconductor member extends parallel to the central axis of said inner andouter conductors.

4. A coaxial line oscillator comprising an electron discharge deviceincluding an anode, cathode, and grid, a cathode inner conductor coupledto the cathode, an anode inner conductor coupled to the anode, outerconductors surrounding said inner conductors and coaxial therewith,meanscapacitively coupling the grid to said outer conductors, feed-back meanscomprising a single linear conductor member having a portion thereofextending between the cathode inner conductor and its outer conductorand the remainder extending between said anode inner conductor and itsouter conductor.

5. A coaxial line oscillator comprising an electron discharge deviceincluding an anode, cathode, and grid, a'cathode inner conductor coupledto the cathode, an anode inner conductor coupled to the anode, outerconductors surrounding said inner conductors and coaxial therewith, aconductive disc coupled to said grid and extending toward said outerconductors and forming a capacitive coupling therewith, feed-back meanscomprising a linear conductor member extending between said cathodeinner conductor and its outer conductor and between said anode innerconductor and its outer conductor, said grid disc h/aving openingstherein through which said linearv conductor member extends.

6. A coaxial line oscillator comprising an electron discharge deviceincluding an anode, cathode, and grid, a cathode conductor coupled tothe cathode, an anode inner conductorcoupled to the anode, outerconductors surrounding said inner co-nductors and coaxial therewith,said outer conductors being -coupled to the grid, feed-back meanscomprising a plurality of linear conductor members, each having aportion extending between the cathode inner conductor and its outerconductor and the remainderI extending between the anode inner conductorand its outer conductor, said linear conductor members beingsymmetrically `disposed about said inner conductors.

7. A transmission line oscillator, comprising' l an electron dischargedevice including an anode,

cathode, and grid, a. cathode'transmission line coupled to the cathodeand grid, an anode transmission line coupled to the anode andA grid,each of said transmission lines including twol con;

ductors, feed-back means comprising a linear conductor extending betweenthe Y'conductors of 'the cathode transmission line and the conductorsofthe anode transmission line, and means for varying the eifective lengthof said conductors comprising a pair of slidable conductive mem-M bers,one of said slidable members coupling the conductors of the cathodetransmissionline to each other and to the linear conductor, andthe otherof said slidable members coup-ling the conductors of saidv anodetransmission line to each other and to the linear conductor, saidslidable members being adapted to be moved to select the points at whichsaid conductors are coupled to each other. Y

8. A coaxial line oscillator comprisingl an electron discharge deviceincluding an anode, cathode, and grid, a cathode inner conductor coupledto thev cathode, van anode inner conductor coupled tothe anode,outer'conducto'rsV surrounding said inner conductors and coaxialtherewith, said outer conductors being coupled to the'grid, feed-backmeans comprising a linear conductor member extending between the cathodeinner conductor and its outer conductor and rbetween the anode innerconductor and its outer conductor, and means vfor varying the effectivelength of said conductors comprising a pair of slidable conductivemembers, one of said slidable members coupling the cathodeinner-conductor, its outer conductor, and the linear conductor, theother of said sllidable members coupling the anode inner conductor, itsouter conductor, and the linear conductor, said slidable members beingadapted to be moved to select the points at which said conductors arecoupled to each other.

9. A coaxial line oscillator according to claim 2 further includingmeans for varying the effective length of said conductors comprising apair of slidable conductive discs each having a central opening therein,the cathode inner conductor passing through one of said openings, andthe anode inner conductor passing through another of said openings,means on each of said discs adjacent said opening for contacting theinner conductor within said opening, means on each of said discsadjacent the circumference thereof for contacting the inner surface ofthe outer conductor thereadjacent, each of said discs further having anopening for the accommodation of said linear conductor, and means oneach of said discs adjacent said last-mentioned opening for makingcontact with said linear conductor.

10. A transmission line oscillator comprising an electron dischargedevice including an anode, cathode, and grid, a cathode transmissionline coupled to the cathode, an anode transmission line coupled to theanode, feed-back means comprising a linear conductor connected to bothsaid transmission lines, separate disc means connected in eachtransmission line, said disc means being also connected to said linearconductor for varying the effective length of the linear conductor Whenthe lines are tuned to thereby control the feed-back, and meansindependent of said tuning means for controlling the feed-backcomprising a tuning stub having its inner conductor connected with saidlinear conductor, and means for tuning said stub.

11. A transmission line oscillator according to claim wherein the outerconductor of said stub is connected to the outer conductor of one ofsaid transmission lines.

12. A transmission line oscillator according to claim 7 furtherincluding means for independently tuning said linear conductorcomprising a tuning stub carried on said slidable member and effectivelyinterposed between slidable member and said linear conductor, saidlinear conductor forming the inner conductor of said tuning stub.

13. A coaxial line oscillator comprising an electron discharge deviceincluding an anode,

cathode, and grid, a cathode inner conductor coupled to the cathode, ananode inner conductor coupled to the anode,A outer conductorssurrounding said inner conductors and coaxial therewith, a grid discconnected to the grid and coupled to said outer conductors, said dischaving openings therein, feed-back means comprising a single linearconductor member having a portion thereof extending between the cathodeinner conductor and its outer conductor and the remainder extendingbetween the anode inner conductor and its outer conductor, said linearconductor member extending through an opening in said grid disc.

14. A coaxial line oscillator according to claim 6 in which conductivetuning members are connected across the cathode inner and outerconductors and the anode inner and outer conductors and to the feed-backconductor members and in which the cross section and number of saidfeed-back conductor members are chosen with respect to other constantsof said oscillator so that optimum feed-back is obtained over apredetermined range of frequencies.

15. A transmission line oscillator comprising an electrondischargeievice including an anode, cathode, and a grid, a cathodetransmission line coupled to the cathode, an anode transmission linecoupled to the anode, feedback means connected between the transmissionlines, movable conductors connected across said transmission lines fortuning the transmission lines and conductive connecting means betweensaid feedback means and said conductors for varying the effect of saidfeedback means when said conductors are moved. A

16. A transmission line oscillator comprising an electron dischargedevice including an anode. cathode, and grid, separate anode and cathodetransmission lines coupled between the anode and grid and the cathodeand grid respectively, feedback meansl comprising a linear conductorinsulated from the grid and extending through both said transmissionlines, movable conductors connected across said transmission lines andto said linear conductor for tum'ng the transmission lines and forvarying the effect of said feedback means when said transmission linesare tuned.

EVERT M. OSTLUND.

REFERENCES CITED The following references are of record in the le ofthis patent:

Hae May 21, 1946

